Ianto sits forward to watch John draw and to listen to his explanation. Picking his coffee up again to have something to do with his hands so that he's not just quietly gaping instead. It's not so much the gates themselves that catch him up, really. It's John's explanation. He's never really done this sort of instructional affair in front of Ianto before and he's -- impressed. Has he really just done those equations in his head in the moment? Does he really understand these gates as well as he sounds like he does? All this talk of constellations and -- space as a cube. It is a little difficult to wrap your head around, and John's always so. Not that Ianto doesn't think he has it in him, it's just that between all the Deadpool jokes and pop culture references, this math lesson he's just spouted is something else, and it's very...

He takes a long, slow sip of his coffee to give himself time to collect his thoughts.

"Our Rift is a naturally occurring, unpredictable phenomenon," he points out, just in case that hadn't been clear from the start. "We got ourselves into a lot of trouble when we went mucking about, trying to use it for our own purposes." He glances up at John. "But I've heard of other devices that do the same thing. Roughly. Jack had one, he. A vortex manipulator, he called it. I think it worked using the same idea, dialing in an address. Using numbers, though, on his wrist strap. I'm not quite sure, it didn't work anymore..."